I have heard both – one source told me you could count them on the fingers of one hand, another suggested 10 to 15. I also recalled how Lord Spicer described the downfall of Iain Duncan Smith in his memoirs, and the great efforts he made to protect the guarantee of anonymity the party rules afford those who write the letters.

Now, I don't know whether Mr Brady is running things differently. Maybe he is keeping a running tally and sharing it with colleagues in a way that would allow it to leak out. But I rather doubt it. Of course, it may be the case that those who have written letters are parading themselves in the tea rooms, in the manner of Derek Conway waving his letter to the television cameras before delivering it to the Chairman of the '22. Maybe some are, but again I have no evidence of it. As I have argued before, it would require things to get far, far worse before the prospect of a leadership challenge can become remotely credible. But for the irreconcilables who want to do in Dave, the secrecy of the system allows them to whisper anything they like, knowing that it cannot be disproved. For all we know, Mr Brady may have received no letters at all. Or his postbag may be bulging since the reshuffle. But I would caution against believing any of these numbers, unless Mr Brady issues a press release.